The present invention relates to tuyeres for use in the processing of metals in liquid, solid or pasty state.
Tuyeres used in metallurgy can be simple (with a single tube), double (with two concentric tubes) or multiple (with several concentric tubes).
They can serve for the introduction either of gases, oxidizers, neutral substances or reducing agents, or of liquids, for example of liquids for protecting tuyeres against hot wear, or of powdered, oxidizing, reducing, or slag-making materials.
The usual method for transporting or introducing a powered material into a metallurgical container consists of suspending this powder in a carrier gas. This method has three drawbacks in the case of a metallurgical operation:
(a) It results in a consumption of carrier gas which is not negligible. PA1 (b) The carrier gas, dissolving at least partly in the metal bath, may be troublesome in the processing of the metal being treated, and also in the exhaust gases. PA1 (c) The powder thus suspended generally has a pronounced abrasive effect on the walls of the ducts and of the tubes that it traverses.
Another method, known in the domain of transportation of petroleum products, but not applied in metallurgy, consists of introducing the viscous or powdered material under increased pressure by any known mechanical means, such as an Archimedes screw, into a tube or into a duct whose inner wall is coated with a lubricating liquid film introduced from place to place along the tube or of the duct. In this way the drawbacks of the previously described method are avoided.
On the other hand, in many cases of processing a metal in a liquid state, it is useful, sometimes even indispensable, for the refinery gas, e.g., an oxidizing gas, to be kept out of contact with the powdered substance, e.g., powdered coal.
It is an object of the present invention to provide a tuyere useful in methods of processing metals in a liquid state or even solid or pasty state, enabling the simultaneous or separate introduction of at least one gas and one powdered material, without using any carrier gas for said powdered substance and without causing any abrasive action by the latter.